On most prior art exercise machines, when exercising the leg muscles, the user engages a foot engaging member, typically in the form of a plate or footboard on which the user rests his feet, and exerts back and forth movement thereagainst for exercising the legs. The foot engaging member is operatively connected to a resistance in the form of a stack of metal plates for providing resistance against movement of the foot engaging member during exercise movement Typically, during movement, as the leg extends and pushes the foot engaging member along its eccentric path of travel, the angle of inclination of the lower leg and tibia constantly changes.
Heretofore, most prior art machines for exercising the leg have been constructed to include a foot engaging member which is movable in a back and forth somewhat arcuate or eccentric path of travel where the rate of angle change of the foot engaging member during pivotal movement is substantially constant so that the imposed forces are not properly directed up the lower leg and tibia. For example, in commonly assigned U.S. Pat. No. 4,511,137 to Jones, the foot engaging member is attached to the lower portion of a lever arm. The lever arm is pivotally mounted in a medial location thereon between two frame members. During back and forth exercise movement, the lever and foot engaging member attached thereto rotate about a fixed axis of rotation. The maximum exercise efficiency is not obtained because during extension and retraction of the lower leg during exercise, the forces normal to the footboard and exerted against the leg are not always exerted up the lower leg and tibia. The semi-circular movement of the foot engaging member does not compensate for the constantly changing angle in movement of the lower leg and tibia during exercise.